Create a shared component

You can create both managed and unmanaged shared components.

Create an unmanaged shared component

To create an unmanaged shared component, create a struct that implements the marker interface ISharedComponentData.

The following code sample shows an unmanaged shared component:

public struct ExampleUnmanagedSharedComponent : ISharedComponentData
{
    public int Value;
}

To override the way that a shared component is checked for equality, you can implement the IEquatable<> interface, and ensure public override int GetHashCode() is implemented. Entities then internally uses these methods to compare shared components for equality, and therefore partitions entities differently that way. You can also put [BurstCompile] on these methods, and they will be compiled with Burst if they comply with Burst's restrictions.

Create a managed shared component

If you create a shared component struct that has any managed fields (such as class types like strings), that component will be treated as a managed shared component. In that case, you also must implement IEquatable<>, and ensure public override int GetHashCode() is implemented. The equality methods are necessary to ensure comparisons don't generate unnecessary managed allocations due to implicit boxing when using the default Equals and GetHashCode implementations.

In contrast to IComponentData components, all shared components must be structs, irrespective of whether they are managed or unmanaged.

The following code sample shows a managed shared component:

public struct ExampleManagedSharedComponent : ISharedComponentData, IEquatable<ExampleManagedSharedComponent>
{
    public string Value; // A managed field type

    public bool Equals(ExampleManagedSharedComponent other)
    {
        return Value.Equals(other.Value);
    }

    public override int GetHashCode()
    {
        return Value.GetHashCode();
    }
}